Grain structure simulation in a large-scale casting made of VZhL14N-VI nickel-base superalloy

The study addresses the problem of predicting the grain structure in large-scale castings made of the VZhL14N-VI nickel-base superalloy, which are bodies of revolution with very thin walls. To this end, the ProCast casting simulation software was used, including its CAFE module for grain structure prediction. Cooling rates in various areas of the casting were determined by computer simulation. Grain size measurements were then performed on real samples produced under industrial conditions at PJSC UEC Kuznetsov (Samara, Russia), and the correlation between grain size and cooling rate was established. It was found that grain size is affected not only by the cooling rate, but also by the geometric features of the casting, particularly its thermal modulus (according to Chvorinov’s rule). The results show that ProCast can be effectively used to predict casting defects in large-scale castings made of nickel-base superalloys. A comparison of the temperature-dependent density, specific heat capacity, and thermal conductivity of the VZhL14N-VI alloy – obtained through both direct measurements and ProCast thermodynamic database calculations – showed that the computed data are sufficiently accurate for use in casting process simulations. The CAFE module was found to be applicable for predicting grain structure in castings; however, accurate simulation requires the specification of key parameters, primarily the degree of undercooling during solidification and the number of grain nuclei in the alloy. Since these parameters cannot be measured directly, further research is required to determine them.